Exploitation Of The 12Cr1MoVG Cold-drawn Seamless Steel Tube

Steel tubes are a kind of metal materials which have been widely used in industry, and they are also very important for national economy. The high-pressured boiler tubes are one kind of seamless steel tubes with high-tech and high affixation value. The rapid development of power industry has greatly promoted the development and production of high-pressured boiler tubes. The development of 12Cr1MoVG cold-drawn seamless steel tubes used in high-pressure boiler not only could increase the varieties of products in our factory, but also expand our market share and strengthen our market competitiveness.Based on the requirement of our factory we developed 12Cr1MoVG cold-drawn seamless steel tubes. The main achievements are as follows:①Theoretically design of the heat treatment processing parameters of tube billets, moulds and processing parameters of hot-rolling and cold-drawing, and the heat treatment processing parameters of the semi-products and final products of the 12Cr1MoVG cold-drawn seamless steel tubes;②The optimized heat treatment processing parameters of the tube billets are: The furnace temperature should be controlled in 1250～1320℃, the steel temperature should be controlled in 1180～1220℃for 80～90 minutes, and then tube billets should be punched at the temperature of 1160～1180℃;③The parameters of the rollers of hot rolling punching mills are: The maximum diameter of 600mm with total length of 350 mm, the length of calibrating strap is 10mm, the entrance cone of 190mm with the gradient of 3.5°, the export cone of 150mm with the gradient of 3°;④design the table of hot-rolled piercing and the deformation of each cold-drawing pass;⑤ The optimized heat treatment processing parameters for final products are as follows: preheating temperature of the normalizing is 980～1000℃and then holding in the temperature of 880～900℃; preheating temperature of the tempering is 730 -750℃and then holding in the temperature of 700～720℃;⑥Eliminate practical problems during production, such as excessive consumption of the hot-rolled balls, the instability of the outer diameter and wall thickness of the semi-tubes, the serious fracture of the plugs during cold-drawing, the slit of the semi-products during annealing and the final products during heat treatment, and the inaccurate temperature of the furnace etc..